1. Field of the Invention
The present invention is directed to explosive welding of pipe. More particularly, the invention is concerned with a collar or sleeve with a formed explosive for explosive welding of hollow cylinders such as pipe. In its more specific aspects, the invention is directed to apparatus for explosive pipe welding in which a formed explosive mass and a collar of particular shapes are employed in explosive welding of two hollow cylinders or sections of pipe together.
2. Description of the Prior Art
Welding of sections of pipe together by the action of explosives is well known. It has also been taught to use interiorly arranged mandrels in welding of pipe to prevent collapse thereof. The prior art also teaches the use of pipe collars for welding pipe by explosive action. Such collars have been formed to provide an angle with the exterior of the pipe but the collars are usually of the same thickness throughout and so is the explosive employed. Likewise, high explosives have been arranged on the exterior of the collar as a cord which is detonated. None of the prior art, however, teaches or makes obvious the present invention wherein an expandable and compressible mandrel is employed which is easily movable through the pipe after weldment of one section to another.
Moreover, the prior art does not teach the use of such a mandrel with a particular type of collar and arrangement of explosive or use of the mandrel, collar, and a particular form of explosive.
Prior art considered with respect to this invention includes the following patents: U.S. Pat. Nos. 3,111,327, 3,290,771, 3,264,731, 2,367,206, 3,137,937, 3,535,767, 402,107, 2,909,951, 3,263,324, 3,563,713, 1,240,326, 3,197,855, 3,343,248, 1,770,649, 1.642,825, 3,308,532, 3,434,194, 2,167,896, 1,878,725, 3,313,021, 2,779,279, 3,570,109, 1,937,644, 3,455,017, 3,290,770, 3,263,323, 3,055,095, 3,434,197, and Belgian Pat. No. 655,943